Tony, Most UHF mobile notch-only flatpack duplexers will work fine below 50 watts at a 5 MHz split- but their performance rapidly deteriorates when operated outside of their stated band limits. For example, a commercial-band mobile duplexer that was manufactured to operate in the 450-470 MHz band will likely perform poorly in the 440-450 MHz Amateur band. Although such a duplexer may SEEM to be working in the Ham 70 cm band, it may have excessive insertion loss that the owner may not realize. That's because the coupling loops are set at the factory and not readily adjustable by the owner.
I once tried to use a commercial-band mobile duplexer on 70 cm in a portable repeater, and was disappointed in its performance- especially receive sensitivity. I then ordered a new Celwave duplexer of the same model, but factory-tuned for my Amateur pair. What a difference! Once the new duplexer was installed, the range of the portable repeater was significantly improved, with no other changes. 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Sunday, June 21, 2009 1:47 PM To: [email protected] Subject: [Repeater-Builder] Mobile Duplexer for 30W repeater ok? Just a double-check question. I'm thinking of buying a UHF mobile duplexer to use with my repeater at home. Since I'll only be running 30 watts, any opinions if this is a bad idea? Most of the older style "cans" are getting higher auction prices, but some mobile packs are pretty reasonable. Thanks, Tony KT9AC
